Messages in this thread Patch in this message | | | From | <> | Subject | [PATCH v6 1/2] smpboot: allow excluding cpus from the smpboot threads | Date | Wed, 8 Apr 2015 15:11:24 -0400 |
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From: Chris Metcalf <cmetcalf@ezchip.com>
This change allows some cores to be excluded from running the smp_hotplug_thread tasks. The motivating example for this is the watchdog threads, which by default we don't want to run on any enabled nohz_full cores.
Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com> --- v6: change from an "exclude" data pointer to a more generic valid_cpu() callback [Frederic]
include/linux/smpboot.h | 3 +++ kernel/smpboot.c | 11 ++++++++--- 2 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/include/linux/smpboot.h b/include/linux/smpboot.h index d600afb21926..4648a4576ae4 100644 --- a/include/linux/smpboot.h +++ b/include/linux/smpboot.h @@ -27,6 +27,8 @@ struct smpboot_thread_data; * @pre_unpark: Optional unpark function, called before the thread is * unparked (cpu online). This is not guaranteed to be * called on the target cpu of the thread. Careful! + * @valid_cpu: Optional function, called when creating the threads, + * to limit the set of cpus on which threads are created. * @selfparking: Thread is not parked by the park function. * @thread_comm: The base name of the thread */ @@ -41,6 +43,7 @@ struct smp_hotplug_thread { void (*park)(unsigned int cpu); void (*unpark)(unsigned int cpu); void (*pre_unpark)(unsigned int cpu); + int (*valid_cpu)(unsigned int cpu); bool selfparking; const char *thread_comm; }; diff --git a/kernel/smpboot.c b/kernel/smpboot.c index c697f73d82d6..6ffc2dacb94a 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -173,6 +173,9 @@ __smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu) if (tsk) return 0; + if (ht->valid_cpu && !ht->valid_cpu(cpu)) + return 0; + td = kzalloc_node(sizeof(*td), GFP_KERNEL, cpu_to_node(cpu)); if (!td) return -ENOMEM; @@ -221,9 +224,11 @@ static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cp { struct task_struct *tsk = *per_cpu_ptr(ht->store, cpu); - if (ht->pre_unpark) - ht->pre_unpark(cpu); - kthread_unpark(tsk); + if (tsk) { + if (ht->pre_unpark) + ht->pre_unpark(cpu); + kthread_unpark(tsk); + } } void smpboot_unpark_threads(unsigned int cpu) -- 2.1.2
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